The present invention relates to semiconductor integrated circuit devices and methods for testing same, and especially relates to an improvement for electron beam (EB) test technology.
As one of the test means for semiconductor integrated circuit chip, EB testers are widely used. The EB tester is an apparatus for observing the state (such as presence of a disconnection or a short circuit) of a signal wire on the chip which depends on a detected output of reflected electrons or secondary electrons which are responsive to the local electric potential. Of several test mode, the image test mode is often employed. In the image test mode one observes the electric potentials of signal wires in a certain area of the chip at a certain time.
In practice, the use of the image mode test in an EB tester has the disadvantage that the area on the chip that can be tested at one time is limited to about 250 .mu.m.times.250 .mu.m at most due to the large memory capacity required to store the image. Therefore, although the EB tester is useful for specified portions of the chip, it is not practical in the case of testing the entire chip, because of the enormous time and effort involved. Thus, it is difficult to judge the quality of chips only by using the EB tester.